Process for producing colored shaped article from curable resin, colored shaped article produced from curable resin, and shaping apparatus

ABSTRACT

In coloration of a shaped article composed of a curable resin, the addition operation can be reliably conducted and a reliable coloration effect can be obtained in both the single-color addition and in the multicolor addition. A liquid-phase, non-colored photo-curable resin is cured by irradiation with laser light and a lowermost layer  5   n  is formed. A liquid-phase, photo-curable resin is applied on the upper surface thereof and a colored layer  5   n-1  comprising a cured non-colored region and a liquid-phase pool region is formed. A color ink is drop-wise added to the liquid-phase pool region. The pool region is irradiated with laser light and cured to the same hardness as that of the non-colored region. A block-like coating film having the prescribed thickness if formed from the surface coating film produced by the color ink covering the pool region. As a result, the formation of the next layer (colored layer  5   n-2 ) on the upper surface of colored layer  5   n-1  can be conducted without obstacles. Colored layer  5   n-2  through colored layer  5   3  are formed by repeating this process, a colored layer  5   2  is formed on the upper surface of colored layer  5   3 , and then the uppermost layer  5   1  is formed on the colored layer  5   2 .

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a process for producing coloredshaped article from curable resin, colored shaped article produced fromcurable resin, and shaping apparatus.

[0003] 2. Description of the Related Art

[0004] Coloration of shaped article produced by a photo-model creationmethod, that is, by lamination and shaping using laser beam irradiationof a photo-curable resin is greatly limited by the color (usually, asemitransparent color) inherent to the resin itself. For this reason, amethod has been used by which a colorant was added to the producedshaped article upon completion of a series of lamination and shapingoperations.

[0005] However, with the above-mentioned conventional coloration method,large-scale equipment is required to add a colorant to the shapedarticle. Another problem is that when the object of coloration is ashaped article having a complex shape, or when a shaped article having acomplex shape is the object of coloration, as mentioned above, andmulticolor addition is conducted which uses a plurality of colorants,the addition operation itself is difficult to implement with theconventional equipment and there are portions that cannot be coloredbecause of complex shape of the shaped article.

[0006] Accordingly, with the foregoing in view, a method has beenattempted by which a colorant is added on the upper surface of thelayers each time the layer is formed by the above-mentioned photo-modelcreation method, that is, a method for curing a photo-curable resin bylaser beam irradiation. In the shaped article having a colorant addedthereto by this method, as shown in FIG. 1, the thickness h′ of coatinglayers 3 ₁˜3 _(n) formed from a colorant is much less than the thicknessh of layers 1 ₁˜1 _(n) formed from the photo-curable resin, but when theshaped article is viewed from the upper surface, the color of thecolorant appears as a color of the shaped article.

[0007] However, when the shaped article is viewed from the side surface,since the thickness h′ of the coating layers 3 ₁˜3 _(n) is very small,as mentioned above, the color (usually, a semitransparent color)inherent to the resin itself, rather than the color of the colorant,appears as the color of the shaped article. The resulting problem isthat the reliable coloration effect cannot be obtained and, therefore,the above-described colorant addition method cannot be consideredeffective.

SUMMARY OF THE INVENTION

[0008] Accordingly, it is an object of the present invention to conductreliably the addition operation and to obtain a reliable colorationeffect in coloration of a shaped article composed of a curable resin,not only in case of a single-color addition employing a single colorant,but also in case of multicolor addition using a plurality of colorants.

[0009] Another object of the present invention is to conduct reliablythe addition operation and to obtain a reliable coloration effect incoloration of a shaped article composed of a curable resin, withoutusing a large-scale equipment.

[0010] The colored shaped article composed of a curable resin, which isthe first aspect of the present invention, comprises a plurality oflayers formed by lamination and shaping of a curable resin, wherein atleast one layer of the plurality of layers has a non-colored regionwhere no colorant was added and a colored region formed by adding acolorant, and the colored region is formed so that the color of thecolorant can be recognized from all directions of the completed coloredshaped article.

[0011] With such a configuration, since the colored region is formed sothat the color of the colorant can be recognized from all directions ofthe completed colored shaped article, a reliable coloration effect canbe obtained.

[0012] In the preferred embodiment relating to the first aspect of thepresent invention, a photo-curable resin is used as the curable resin.Examples of suitable colorants include compositions prepared by anon-volatile ink using a pigment for ceramics, a colorless finelypowdered dye which is colored under UV irradiation, or an ink using apigment or dye as the raw material with a liquid-phase, curable resin,compositions prepared by mixing a pigment or dye with a liquid-phasesolvent other than a curable resin, such compositions having goodaffinity with the curable resin, compositions prepared by mixing coloredfibers or color beads with a liquid-phase, curable resin, andcompositions prepared by mixing colored fibers or color beads with aliquid-phase solvent other than a curable resin, such compositionshaving good affinity with the curable resin.

[0013] A process for producing colored shaped article from curable resinin accordance with the second aspect of the present invention relates toa colored shaped article comprising a plurality of layers formed bylamination and shaping of a curable resin, wherein at least one layer ofthe plurality of layers has a non-colored region where no colorant wasadded and a colored region formed by adding a colorant, this processcomprising a step of forming the colored region in the liquid-phase,curable resin so that the color of the colorant can be recognized fromall directions of the completed colored shaped article and then curingthe curable resin and forming a colored region, and a step of curing thecurable resin in a liquid-phase state and forming the non-coloredregion.

[0014] A process for producing colored shaped article from curable resinin accordance with the third aspect of the present invention relates toa colored shaped article comprising a plurality of layers formed bylamination and shaping of a curable resin, wherein at least one layer ofthe plurality of layers has a colored region formed by adding acolorant, this process comprising the steps of forming an external wallby curing a region of prescribed width along the contour line of thecolored region, adding a colorant to the region in a liquid-phase stateinside the external wall, and curing said colored region.

[0015] In the preferred embodiment relating to the third aspect of thepresent invention, a step of forming partition walls by curing thepartition zones of prescribed thickness inside the region which is to becolored is implemented prior to the step of adding the colorant.Furthermore, the above-mentioned colored region is formed by adding theprescribed amounts of the colorant at the prescribed distance intervalsby using an addition mechanism displaced by feedback-corrected pulsesignals. The step of adding the colorant comprises a step of removingthe liquid-phase, curable resin present in the region which is to becolored and a step of adding the colorant into the region after theremoval of the curable resin. Furthermore, the addition of colorants ofa plurality of colors into the above-mentioned region which is to becolored is conducted by adding the colorants in a sequence starting fromthe colorant with a color of the highest priority based on thepredetermined order of priority. This is conducted to prevent thereduction in size of the colored region caused by multicolor additionand to facilitate recognition of each color.

[0016] A shaping apparatus according to the fourth aspect of the presentinvention forms a desired shaped article by lamination and shaping of aliquid-phase, curable resin, this apparatus comprising an additionmechanism that can be displaced in at least the horizontal direction toadd a liquid-phase or powdered colorant to the liquid-phase, curableresin.

[0017] In the preferred embodiment relating to the fourth aspect of thepresent invention, a needle mechanism comprising a first colorant supplyhole extending, for example, in the axial direction thereof and a secondcolorant hole perpendicular to the axial direction is employed as theaddition mechanism. Such a needle mechanism has a strength and shapeallowing for insertion into the liquid-phase, curable resin andthree-dimensional displacement in the curable resin.

[0018] An apparatus for the implementation of coloration and shapingwill be described below. For example, an apparatus with a structure inwhich a dispenser is supported on a positioning/moving mechanism so thatit can be two-dimensionally displaced, such as an XY plotter, or anapparatus with a structure in which a dispenser is supported on apositioning/moving mechanism so that it can be three-dimensionallydisplaced, such as a robot arm, can be used as the above-mentionedapparatus. Furthermore, apparatuses with a structure in which amulti-nozzle head (contains no needle-like parts) such as a head of atypical ink-jet printer is supported on an XY plotter or robot arm canbe also used as the above-mentioned apparatus. When an XY plotter isused for the positioning/moving mechanism, the control of various partsof the apparatus is conducted, for example, based on a standard XYtable, and when a robot arm is used instead of the XY plotter, thecontrol of various parts of the apparatus is conducted, for example,based on a standard XYZ table. In any case, the above-mentionedapparatus is not limited to the apparatuses having the configurationdescribed above.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a cross-sectional view of a colored shaped articlecomposed of a photo-curable resin colored by the conventional colorantaddition method;

[0020]FIG. 2 is a cross-sectional view illustrating an example of thecolored shaped article composed of a photo-curable resin relating to anembodiment of the present invention;

[0021]FIG. 3 is a perspective view of a colored layer composed of aphoto-curable resin, which constitutes the colored shaped article shownin FIG. 2;

[0022]FIG. 4 is a perspective view of a colored layer composed of aphoto-curable resin of a type different from that in FIG. 3, whichconstitutes the colored shaped article shown in FIG. 2;

[0023]FIG. 5 illustrates an example of a method for forming a coloredlayer composed of a photo-curable resin, which is shown in FIG. 3;

[0024]FIG. 6 illustrates a modification of the formation method shown inFIG. 5;

[0025]FIG. 7 illustrates an example of the method for coloring a layercomposed of a photo-curable resin, while suppressing the build-up of thecolorant (color ink);

[0026]FIG. 8 illustrates another example of the coloration method shownin FIG. 7;

[0027]FIG. 9 illustrates still another example of the coloration methodshown in FIG. 7 and compares the results obtained by the colorationmethods shown in FIG. 7 and FIG. 8;

[0028]FIG. 10 illustrates an example of the method for coloration oflayers in the colored shaped article composed of a photo-curable resinbased on the method shown in FIG. 7, in a state in which the colorationregions are averaged over the entire shaped article; and

[0029]FIG. 11 illustrates an example of the method for multicoloraddition to a layer composed of a photo-curable resin, without thereduction in size of the colored region.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The embodiments of the present invention will be described indetail below with reference to the appended figures.

[0031]FIG. 2 is a cross-sectional view illustrating an example of thecolored shaped article composed of photo-curable resins relating to anembodiment of the present invention.

[0032] The colored shaped article has a structure obtained by laminationand shaping of a photo-curable resin. The shape of the entire shapedarticle is not limited to any specific shape, and a variety of shapessuch as rectangular (square), round, elliptical, and the like can beassumed for a shape viewed from above or below thereof. In the coloredshaped article, as shown in FIG. 2, the uppermost layer 5 ₁ and alowermost layer 5 _(n) are the layers (usual layers) composed of anon-colored photo-curable resin, and a plurality of layers laminatedbetween the uppermost layer 5 ₁ and lowermost layer 5 _(n) are thelayers (colored layers) 5 ₂ through 5 _(n-1) composed of thephoto-curable resin colored in various colors.

[0033] Both usual layers 5 ₁, 5 _(n) are provided to prevent thedecrease in strength of the colored shaped article, which is the curedproduct, and to protect the coating film comprising a colorant (namely,various color inks, for example volatile inks using a pigment forceramics). The usual layers 5 ₁, 5 _(n) are formed only by a curingprocess (the process in which a non-cured photo-curable resin, that is,a liquid-phase photo-curable resin is cured by illuminating with a laserlight) and have the respective prescribed thickness (N layer fraction).

[0034]FIG. 3 is a perspective view illustrating a colored layer used asa colored layer 5 ₂ positioned in the uppermost portion and a coloredlayer 5 _(n-1) positioned in the lowermost portion, of the coloredlayers 5 ₂˜5 _(n-1) shown in FIG. 2.

[0035] Those colored layers 5 ₂, 5 _(n-1) are formed so that the colorscoated from the upper and lower surfaces of the colored shaped articlecan be recognized and they comprise a non-colored region A called anouter frame (external wall) and a colored region B formed in theso-called pool region surrounded by the external wall. The non-coloredregion A is formed only by the above-described curing process, similarlyto the usual layers (5 ₁, 5 _(n)).

[0036] On the other hand, the colored region B is formed by implementinga process (coloring process) in which the non-cured state (that is, aliquid-phase state) is maintained, without irradiation with the laserbeam, during curing of the non-colored region A and a colorant is addedto the region in the non-cured state, and then by implementing a curingprocess similar to the above-described process on this region. Curingafter coloration of the region in the non-cured state is implemented asprocessing designed to prevent a negative effect on the formation of thenext layer on the aforesaid layer. Furthermore, coloration, for example,with a color ink, of the region in the non-cured state which becomes thecolored region B is conducted, for example, by dropping the color inkonto the region in the non-cured state from a nozzle 7 of a dispenser(not shown in the figure) which is an addition mechanism attached to thefront end of a two-axis (XY) robot arm (not shown in the figure).

[0037]FIG. 4 is a perspective view illustrating the colored layers usedas all remaining layers (that is, colored layers 5 ₃ through 5 _(n-2))sandwiched between the colored layers 5 ₂, 5 _(n-1) of the coloredlayers 5 ₂˜5 _(n-1) shown in FIG. 2.

[0038] The colored layers 5 ₃ through 5 _(n-2) are employed for theapplied colors to be visible from the side surface of the colored shapedarticle, each of them having an outer-contour non-colored region Ccalled an external wall, a colored region D formed in a region called agroove of a prescribed width that was formed over the entire perimeteralong the inner side of the external wall, and an inner-contournon-colored region E on in the inner side of the groove. Theouter-contour and inner-contour non-colored regions (C, E) are bothformed by the curing process similar to that used to form theabove-described usual layers (5 ₁, 5 _(n)).

[0039] On the other hand, the colored region D, similarly to the coloredlayers (5 ₂, 5 _(n-1)) shown in FIG. 3 is formed by maintaining thenon-cured state, without irradiation with the laser light, during curingof the outer-contour and inner-contour non-colored regions (C, E) andimplementing a coloring process on the region in the non-cured state,and then implementing the curing process (processing creating noobstacles for the formation of the next layer) similar to theabove-described process on this region. Furthermore, coloration, forexample, with a color ink, of the region in the non-cured state whichbecomes the colored region D is conducted by dropping the color ink ontothe region in the non-cured state from a nozzle 7 of a dispenser (notshown in the figure) similar to the above-described dispenser.

[0040] The colored shaped article of the above-described configurationcan be fabricated by the following process.

[0041] First, a non-colored photo-curable resin in a non-cured state(liquid-phase state) is irradiated with a laser beam. As a result, thephoto-curable resin is cured and a usual layer with a thickness of Nlayer fraction is formed as a lowermost layer 5 _(n). Then, aliquid-phase photo-curable resin is coated to the prescribed thicknesson the upper surface of the lowermost layer 5 _(n), only in the regioncorresponding to the external wall, where the colored layer 5 _(n-1)shown in FIG. 2 is to be formed, and cured by irradiation with a laserbeam, thereby forming a non-colored region A. As a result, theliquid-phase, photo-curable resin coated on the upper surface oflowermost layer 5 _(n) is separated into the cured non-colored layer Aand a pool which is in a non-cured state (liquid-phase state), that is,a region (the above-described colored region B) which is cured aftercoloration by coating with a color ink. This pool is set to have thesize (dimensions), and shape such as to produce no effect on thelamination and shaping of the colored shaped article.

[0042] Upon such a separation of the liquid-phase photo-curable resininto the cured non-colored region A and the pool in a non-cured state, acolor ink is dropped as a colorant from the nozzle 7 of theabove-mentioned dispenser (not shown in the figure). It is preferredthat the color ink used has a very good affinity with the liquid-phasephoto-curable resin. In the present embodiment, inks of four colors, red(R), blue (B), yellow (Y), and black (B), are used as the color ink.

[0043] When the color ink is dropped onto the pool, because of theabove-mentioned affinity it diffuses into the photo-curable resin in anon-cured state. As a result, the color ink is added to the entire pool.Once the color ink has been added to the photo-curable resin (that is,the pool) in a non-cured state, the pool is irradiated with a laser beamand the region that becomes the colored region B is cured to the samehardness as the aforesaid non-colored region A. As a result, ablock-like coating film having a constant thickness is produced from thesurface-like coating film formed by the color ink that is applied on thepool.

[0044] Irradiation with a laser beam of the same energy as that used forcuring of the non-colored region A is sometimes insufficient to form thecolored region B by curing the above-mentioned region (pool) of thephoto-curable resin, which is in a liquid-phase state and has a colorink added thereto, to the same hardness as that of the non-cured regionA. In such a case, it is necessary to use a special curing method, forexample, a method of setting a long exposure time during laser beamirradiation or a method of multiple exposure during laser beamirradiation as means for increasing the light energy projected on theregion in a liquid-phase state (that is, the region which is to becomethe colored region B).

[0045] Forming the colored region B by curing the region in aliquid-phase state which has a color ink added thereto makes it possibleto form, without obstacles, the next layer (that is, colored layer 5_(n-2)) on the upper surface of colored layer 5 _(n-1).

[0046] Then, a photo-curable resin is added to the prescribed thicknessonto the upper surface of colored layer 5 _(n-1), and the regioncorresponding to the external wall and inner contour, where the coloredlayer 5 _(n-2) shown in FIG. 2 is to be formed, is cured by irradiationwith a laser beam to obtain an outer-contour non-colored region C and aninner-contour non-colored region E. As a result, the photo-curable resincoated on the upper surface of colored layer 5 _(n-1) is separated intothe cured non-colored regions C, E and a groove in a non-cured state,that is, a region which is to become the above-described colored regionD. The groove, similarly to the above-described pool, is set to have thesize (dimensions), and shape such as to produce no effect on thelamination and shaping of the colored shaped article.

[0047] Once the photo-curable resin has thus been separated into thecured non-colored regions C, E and the groove in a non-cured state, acolor ink having a very good affinity with the photo-curable resin, asin the above-described process, is dropped as a colorant from the nozzle7 of the dispenser (not shown in the figure). Therefore, because of theaffinity, the color ink diffuses into the photo-curable resin which isin a non-cured state. As a result, the color ink is added to the entiregroove. After such an addition of the color ink to the photo-curableresin (that is, the groove) which is in a non-cured state, the groove isirradiated with a laser beam and the region that is to become thecolored region D is cured to the same hardness as that of thenon-colored regions C, E. As a result, a block-like coating film with aconstant thickness is produced from the surface-like coating film formedby the color ink coated on the groove. Similarly to the above-describedprocess, when the region which is to become the colored region D iscured, the irradiation with a laser beam of the same energy as that usedfor curing of the non-colored regions C, E is sometimes insufficient toobtain the hardness of colored region D of the same order as that ofnon-colored regions C, E.

[0048] In such a case, in the laser beam irradiation of the region whichis to become the colored region D, it is also necessary to increase thelight energy projected onto the region in a non-cured state (that is,the colored region D) by using a special curing method, for example, amethod of setting a long exposure time or a method of multiple exposure,similarly to the above-described laser beam irradiation of the regionwhich is to become the colored region B.

[0049] Thus, forming the colored region D by curing the region in aliquid-phase state which has a color ink added thereto makes it possibleto form, without obstacles, the next layer on the upper surface ofcolored layer 5 _(n-2).

[0050] It is suffice that only two patterns, a pool and a groove, beused as the patterns of the regions in a liquid-phase state which are tobecome the colored regions in the colored layers 5 ₂˜5 _(n-1). If theregion in a liquid-phase state is set to have a pool-like shape, colorrecognition can be reliably conducted even when the produced coloredshaping article is viewed from the top-bottom direction. On the otherhand, when the region in a liquid-phase state is set to have agroove-like shape, color recognition can be conducted only when theproduced colored shaped article is viewed from the lateral direction.However, the advantage of such a setting is that the time required forthe coloration process can be shortened and the amount of ink used inthe coloration process can be reduced.

[0051] Once the colored layers 5 _(n-2)˜5 ₃ have been formed by therepetition of the above-described process, a colored layer 5 ₂ havingthe same configuration as the above-described colored layer 5 _(n-1) isformed on the upper surface of colored layer 5 ₃ and then a non-coloredlayer 5 ₁ having the same configuration as the non-colored layer 5 _(n)is formed on the upper surface of colored layer 5 ₂, thereby forming thecolored shaped article.

[0052] The addition of the above-described photo-curable resin (liquidresin) is conducted with a recoater (not shown in the figures) providedin a shaping apparatus (not shown in the figures) used for laminationand shaping of the colored shaped article. Furthermore, connectionbetween the nozzle 7 of dispenser (not shown in the figures) and asyringe (tank) (not shown in the figures) is provided with a tube (notshown in the figures).

[0053] Furthermore, a controller (not shown in the figures) controllingthe units of the shaping apparatus contains shaping data used when theusual layers (5 ₁, 5 _(n)) are formed, shaping data used when thecolored layers (5 ₂, 5 _(n-1)) are formed, and shaping data used whenthe colored layers (5 ₃ through 5 _(n-2)) are formed. The controller(not shown in the figures) provides for lamination and shaping of theabove-mentioned colored shaped article by appropriately using a varietyof the shaping data.

[0054] In the above-described embodiment, a colorant was added to thelayers (5 ₂ through 5 _(n-1)), which are to be colored, in the processof lamination and shaping of the colored shaped article. Therefore, theprocess for adding the colorant after the completion of the series ofshaping operations was unnecessary.

[0055] Furthermore, since the colorant was added in the course oflamination and shaping process, the automation of colorant additionoperation can be conducted together with the automation of shapingoperation carried out with the shaping apparatus. Therefore, theaddition operation can be conducted while the shaping operation is beingconducted, and not only single-color, but also multicolor addition canbe conducted.

[0056] Moreover, since the coating surface of colored layers is sealedinside the colored shaped article, peeling of the coated films from thecolored layers under the effect of external impacts or chemical changescaused by adhesion of reagents and the like is essentially impossible.

[0057]FIG. 5 illustrates an example of a method for forming a layer(colored layer) consisting of a colored photo-curable resin describedwith reference to FIG. 3.

[0058] In FIG. 5, the external wall front surface 9 of theabove-described colored layers (5 ₂, 5 _(n-1)) is formed based on thedata (front surface data) representing the external wall front surface 9determined by slicing the STL data. Furthermore, the external wall innersurface 11 of the colored layers (5 ₂, 5 _(n-1)) is formed based on thedata (inner surface data) determined by offsetting the above-mentionedfront surface data inward through a certain distance. The external wallinner surface 11 is equivalent to the outer periphery of the pool, thatis, the region which is to become the colored region B. Furthermore, arectangular line 13 indicating the trajectory of the position of colorink, that is, the colorant, dropping on the region which is to becomethe colored region B is determined based on the data (data for inkdropping) found by offsetting the inner surface data inward through acertain distance.

[0059] When the colored layers (5 ₃ through 5 _(n-2))shown in FIG. 4 areformed, the external wall front surface 9 is formed based on the frontsurface data, the outer periphery of the groove, that is, the regionwhich is to become the colored region D, is determined on the externalwall inner surface 11, and the inner periphery of the region which is tobecome the colored region D is determined based on the data found byoffsetting the inner surface data inward through a certain distanceexceeding the rectangular line 13 for ink dropping.

[0060] Trial fabrication of colored layers (5 ₂, 5 _(n-1)) shown in FIG.3 and colored layers (5 ₃˜5 _(n-2)) shown in FIG. 4 conducted by theinventors demonstrated that the appropriate thickness of the externalwall produced for setting the pool (or groove) is about 0.5-5.0 mm. Ifthe wall thickness is less than 0.5-5 mm, the color ink drop-wise addedinto the pool (or groove) will ooze out of the pool (groove), and whenthe wall thickness is greater than the above value, the coloration ofthe completed colored shaped article becomes indistinct.

[0061] Furthermore, the rectangular line 13 representing the trajectoryof the color ink dropping position is preferably set in a position at adistance of about 1.0 to 5.0 mm from the external wall inner surface 11,though the diffusion surface area may vary depending on the shape of theformed colored shaped article and the relationship between the surfacetension of the colored ink which is drop-wise added and thephoto-curable resin in a liquid-phase state.

[0062] The composition prepared by dissolving a powder consisting ofcolorless particles of a very small diameter which are characterized bythe ability to be colored under UV irradiation in a photo-curable resinwas used as a dye (color ink) for coloration employed for the test.Since the particles were colorless, they produced no adverse effect onthe UV transmissivity in the photo-curable resin even after they weredrop-wise added to the photo-curable resin in a liquid-phase state.Accordingly, they did not hinder the curing process.

[0063]FIG. 6 illustrates a modification of the formation methoddescribed with reference to FIG. 5

[0064] In this modification, in order to prevent the color ink coated ona portion of the above-described pool region, that is, a portion of theregion which is to become the colored region B, in the colored layers (5₂, 5 _(n-1)) shown in FIG. 3, from flowing out or diffusing from thisregion into other regions, a wall 15 is provided on the outer peripheryof this region. Furthermore, partition walls 17 are also provided toprevent mixing of color inks of different colors when multicoloraddition is conducted on a portion of this region.

[0065] The appropriate thickness of walls 15, 17 is about 0.5-5.0 mm,though it depends on the shape of the region. The wall thickness may bedecreased to facilitate the observation of color provided to aphoto-curable resin in a liquid-phase state. However, if the wallthickness is less than 0.5 to 5.0 mm, there is a possibility that thecolor ink drop-wise added to the region will ooze out of the region.

[0066] An STL data format is employed in the controller (not shown inthe figures) of the shaping apparatus in order to implement theformation method shown in FIG. 6. The STL format by itself has no colorinformation. For this reason, files for each color are created in thecontroller and identification of various colors is executed.

[0067]FIG. 7 illustrates an example of a method for coloring a layerconsisting of a curable resin, while suppressing the build-up of thecolorant (color ink).

[0068] As described above, the color ink dropped onto a photo-curableresin in a liquid-phase state diffuses over the resin liquid surface.Therefore, data (coloration data) used to cause the adhesion of colorink to the photo-curable ink should not be as specific as data (shapingdata) used when the photo-curable resins in a liquid-phase state arelaminated and shaped. If the coloration data are too specific, theamount of added color ink is increased accordingly and the added colorink builds up in the pool region in the colored layers (5 ₂, 5 _(n-1))shown in FIG. 3 or in the groove region in the colored layers (5 ₃˜5_(n-2)) shown in FIG. 4, thereby hindering the above-mentionedlamination and shaping. In order to guard against such a possibility,the so-called thinning of coloration data was conducted. In FIG. 7, inorder to simplify the explanation and graphic representation, thelamination and shaping process is illustrated based on a colored shapedarticle of round shape, as viewed from the upper/lower surface.

[0069] In FIG. 7(a), the colored region F shows shaping data relating toshaping of a colored layer having a disk-like shape. The concentriccircular arc G positioned on the inner periphery thereof represents theoriginal coloration data produced by offsetting the shaping data througha certain distance, that is, the trajectory of nozzle 7 of theabove-mentioned dispenser (not shown in the figure). The so calledthinning of coloration data is conducted according to thebelow-described procedure by using this circular arc G.

[0070] First, as shown in FIG. 7(b), a plurality of equidistant apexesG₁ through G_(n) are determined on the coloration data (circular arc G).More specifically, the apexes G₁ through G_(n) are determined by findingthe coordinates indicating the apexes G₁ through G_(n). Then, as shownin FIG. 7(c), for example, an apex G₁ selected from the apexes G₁˜G_(n)is determined as an initial point P₁ of coloration data and the apex G₃separated from this initial point P₁ by a distance of no less than theprescribed distance t is assumed to be a second point P₂ of colorationdata, following the initial point P₁. By the same procedure, as shown inFIG. 7(d), the third point P₃ of coloration data, . . . , and n-th pointof coloration data, that is, the final point P_(n) is found. The finalpoint P_(n) should be selected so as to be separated from the initialpoint P₁ by a distance of no less than the aforesaid distance t. Thecolorants are added in respective prescribed amounts in the points P₁,P₂, P₃, . . . , P_(n) that were thus selected.

[0071]FIG. 8 illustrates another example of the coloration methoddescribed with reference to FIG. 7.

[0072] As described above, when a photo-curable resin in a liquid-phasestate is coated, there is a possibility that color ink would not diffuseuniformly in the coloration region and coloration defects can beproduced. Accordingly, the below-described measures were taken toprevent such defects.

[0073] Initially, as shown in FIG. 8(a), the color ink was dropped fromthe nozzle 7 of a dispenser (not shown in the figures) located at aheight of 5 to 10 mm above the surface of the photo-curable resin in aliquid-phase state. However, modifying the structure of nozzle 7 so asto obtain a sufficient strength and a shape allowing for insertion intothe photo-curable resin in a liquid-phase state and removal therefrommakes it possible to conduct coloration by inserting the nozzle 7 intothe photo-curable resin in a liquid-phase state, as shown in FIG. 8(b).Inserting the nozzle 7 into the photo-curable resin in a liquid-phasestate allows for coloration in a state in which the color ink wasgreatly diffused. Furthermore, spattering of ink is also prevented andaccurate control of the vertical position of nozzle 7 becomesunnecessary. Moreover, if a nozzle with a plurality of transverse holes7 a˜7 n in a side surface, which is shown in FIG. 8(c), is used as thenozzle 7, the coloration can be conducted in a state in which the colorink was diffused even more significantly.

[0074] With another method for uniformly diffusing the color ink addedto the photo0curable resin in a liquid-phase state in the colorationregion, the color ink is dropped after being heated inside the dispenser(not shown in the figures) or in the nozzle 7. If a color ink is at alow temperature, the viscosity thereof is higher. As a result, thediffusion thereof requires certain time. Therefore, the color ink addedto the non-cured portions of the photo-curable resin, such as theabove-described pool or groove, does not diffuse uniformly andcoloration defects are produced. However, if the color ink dropped uponheating, because the viscosity is low, the ink diffuses within acomparatively short time. As a result, the coloration defects areprevented. Furthermore, the internal structure of nozzle 7 can bemodified to provide for more uniform diffusion of color ink and moreeffective elimination of coloration defects. Thus, a structure may beused in which longitudinal holes opened in the bottom portion of nozzle7 are provided in addition to transverse holes 7 a˜7 n shown in FIG.8(c).

[0075]FIG. 9 shows still another example of the coloration methodillustrated by FIG. 7 and compares the results obtained by thecoloration methods illustrated by FIG. 7 and FIG. 8.

[0076] With the coloration methods illustrated by FIG. 7 and FIG. 8,first, as shown in FIG. 9(a) only the external wall was cured and theregion corresponding to the pool (or groove) was left in a liquid-phasestate. Then, as shown in FIG. 9(b), a color ink was dropped from thenozzle 7 of a dispenser (not shown in the figures) into the pool (orgroove) region which was in a non-cured state. As a result, as shown inFIG. 9(c), a build-up in an amount of the dropped color ink appeared inthe pool (or groove) region, and shaping of the next layer on the uppersurface of the layer shown in the figure was impossible at a laminationpitch with a thickness of no more than the build-up. In other words, asmall lamination pitch could not be set.

[0077] Accordingly, in the present example, as shown in FIG. 9(a), onlythe external wall was cured and the region corresponding to the pool (orgroove) was left in a liquid-phase state. Then, as shown in FIG. 9(d),the photo-curable resin in a liquid-phase state located in the regioncorresponding to the pool (or groove) was sucked out and a color ink wasdropped from the nozzle 7. With such a method, since the photo-curableresin (in a liquid-phase state) located in the region corresponding tothe pool (or groove) was removed, there is no build-up which is causedby the color ink dropping, as shown in FIG. 9(e).

[0078] A method of applying air pressure to the dropping site of colorink is still another means for preventing the build-up of color inkdropped on the non-cured photo-curable resin. Furthermore, a method ofapplying vibrations to the dropping site of color ink is a means forpreventing the build-up of the color ink and also enhancing thediffusion thereof.

[0079] For example, compositions prepared by admixing pigments, dyes, orinks prepared by using them as raw material to the photo-curable resinin a liquid-phase state, and compositions prepared by dissolvingpigments or dyes in solvents other than photo-curable resins in aliquid-phase state can be used as the above-mentioned color ink. As forthe compositions prepared by dissolving pigments or dyes in solventsother than photo-curable resins in a liquid-phase state, they shouldhave affinity with photo-curable resins, in other words, they should nothinder the curing of photo-curable resins. Moreover, compositions usingfibers or color beads instead of pigments and dyes can be also used asthe color ink.

[0080] The explanation given above was based on the assumption that anexternal wall surrounding the pool (or groove) region is present.However, a shaping method which requires no external wall can be alsoimplemented by adding a color ink to a non-cured photo-curable resin ina plurality of cycles. Such a shaping method comprises the followingsteps.

[0081] First, only one layer of a photo-curable resin layer is cured anda thin film is formed by irradiating the photo-curable resin in aliquid-phase state with a laser beam. Then a color ink is added on thethin film according to the offset data (data obtained by offsetting thecontour shape data inward by about 0.5 to 5.0 mm) of shaping data (datarepresenting the contour shape of colored shaped article) of coloredshaped article. When the colored surface is the upper surface or lowersurface of the layer, the color ink is added inside the contour linedetermined by the data obtained by offsetting the contour data of theupper surface or lower surface inward. When the build-up of the colorink thus added is small, the addition of color ink is repeated multipletimes and the build-up of the added color ink is formed within a rangein which the prescribed lamination pitch is not reached. Further, in astate in which the added color ink is sufficiently dried (cured) to adegree producing no adverse effect on the next operation, aphoto-curable resin in a liquid-phase state is added onto the surfacethereof, this resin being required for forming the next layer. Then, thephoto-curable resin in a liquid-phase state is irradiated with a laserbeam according to the shape data of the next layer and the photo-curableresin is cured so as to obtain the prescribed shape.

[0082] The desired colored shaped article is formed by repeating theabove-described process the required number of times.

[0083] With this method, the build-up with a prescribed thickness isformed from a color ink by multiple addition of the color ink. However,instead of adding the color ink, a color sheet having a thickness thatdoes not exceed the lamination pitch may be cut to the desired shape andthen glued to the liquid-phase, photo-curable resin. In such a case, acolor sheet having a thickness that does not exceed the lamination pitchmay be cut to the desired shape after gluing to the liquid-phasephoto-curable resin. A color sheets having a thickness exceeding thelamination pitch is preferably not used because it hinders laminationand shaping.

[0084] Furthermore, a method of adding a viscous color ink, for example,a color resin only one time can be used instead of the method ofmultiple addition of color ink. With such a method, the addition ofcolor resin is conducted while the thickness of coating film formed byadding the color resin is being controlled so that it approaches asclose as possible to the thickness of lamination pitch.

[0085] Furthermore, a method in which a color ink is dropped onto aliquid-phase, photo-curable resin after recoating and the liquid-phasephoto-curable resin is cured faster than the dropped color ink diffusesinto the photo-curable resin can be used as a shaping method that doesnot require the formation of the above-mentioned external wall. In otherwords, with such a method the outflow of color ink into a region whichis not to be colored is prevented by conducting dropping of color inkand curing of the liquid-phase photo-curable resin practically at thesame time.

[0086] Moreover, if the color ink is in a state in which it does notdiffuse in the resin, for example, when the particles of color ink areembedded in a photo-curable resin, the desired colored shaped articlecan be formed by adding (printing) a color ink to the resin afterrecoating (that is, a liquid-phase photo-curable resin), for example, byusing a mechanism similar to that of ink-jet printers and then repeatingthe process of curing the resin for each layer.

[0087]FIG. 10 illustrates an example of a method by which coloration inthe layers of a colored shaped article consisting of a photo-curableresin in a state in which the coloration region is averaged over theentire body, based on the method illustrated by FIG. 7.

[0088] In this example, coloration was conducted by using thinningcoloration data in which the initial points were randomly made differentfor all of the layers, so that in the apexes P₁˜P_(n) (FIG. 10(a))located on a circular arc G obtained by the method illustrated by FIG.7, the thinning coloration data having the apex P₁ as the initial pointwere used for the first layer (FIG. 10(b)), the thinning coloration datahaving the apex P₃ as the initial point were used for the second layer(FIG. 10(c)), and the thinning coloration data having the apex P₂ as theinitial point were used for the third layer (FIG. 10(d)).

[0089] Accordingly, the colorant (color ink) addition regions based onthose coloration data are shifted in each of the layers and, as aresult, the colorant addition regions are averaged and dispersed, asviewed over the entire colored shaped article.

[0090]FIG. 11 illustrates an example of a method for multicolorcoloration of a layer consisting of a curable resin, without decreasingthe size of coloration region.

[0091] In case of multicolor coloration of a colored shaped article,unless the priority or colors in coloration is determined in advance, aregion in which coloration is conducted with a color other than thecolor relating to coloration data will expand, as shown in FIG. 11(a).In the example shown in FIG. 11(a), though the colors of coloration dataare color 1, color 2, and color 3, actually, a portion in which thecoloration region of color 1 and the coloration region of color 2overlap, a portion in which the coloration region of color 1 and thecoloration region of color 3 overlap, a portion in which the colorationregion of color 2 and the coloration region of color 3 overlap, and aportion in which the coloration regions of color 1, color 2, and color 3overlap expand correspondingly. Sometimes coloration is not actuallyconducted in the above-mentioned overlapping regions and partitions areprovided between various coloration regions. In such a case, thepartitioned regions assume an appropriate size, as compared to thecoloration region. As a result, the coloration regions are reduced insize.

[0092] In the present example, a priority of colors was establishedduring coloration. The priority can be freely determined depending onwhat color of the colored shaped article should be conspicuous, inuser's opinion. For example, if among the above-mentioned color 1, color2, and color 3, color 1 should be the most conspicuous, followed bycolor 2, then coloration with the above-mentioned color separation isconducted according to the pattern shown in FIG. 11(b). As a result, thereduction of coloration regions in size caused by the multicoloraddition can be prevented.

[0093] The explanation given above merely related to an embodiment ofthe present invention and obviously imposed no limitation on the presentinvention. Thus, the present invention can be implemented in variousother modifications.

What is claimed is:
 1. A colored shaped article composed of a curableresin, which comprises a plurality of layers formed by lamination andshaping of the curable resin, wherein at least one layer of saidplurality of layers has a non-colored region where no colorant is addedand a colored region formed by adding a colorant; and said coloredregion is formed so that the color of said colorant can be recognizedfrom all directions of said colored shaped article when completed. 2.The colored shaped article composed of a curable resin, according toclaim 1, wherein said colorant is any of non-volatile ink using apigment for ceramics, colorless finely powdered dye which is coloredunder UV irradiation, compositions prepared by mixing an ink using apigment or dye as the raw material with a liquid-phase, curable resin,compositions prepared by mixing a pigment or dye with a liquid-phasesolvent other than a curable resin, and having good affinity with thecurable resin, compositions prepared by mixing colored fibers or colorbeads with a liquid-phase, curable resin, and compositions prepared bymixing colored fibers or color beads with a liquid-phase solvent otherthan a curable resin, and having good affinity with the curable resin.3. A process for producing colored shaped article from curable resin,said colored shaped article comprising a plurality of layers formed bylamination and shaping of a curable resin, wherein at least one layer ofsaid plurality of layers has a non-colored region where no colorant isadded and a colored region formed by adding a colorant, said processcomprising the steps of: forming said colored region in said curableresin in a liquid-phase state by forming the colored region so that thecolor of said colorant can be recognized from all directions of saidcolored shaped article when completed, and then curing the curableresin; and curing the liquid-phase, curable resin and forming thenon-colored region.
 4. A process for producing colored shaped articlecomprising a plurality of layers formed by lamination and shaping of acurable resin, wherein at least one layer of said plurality of layershas a colored region formed by adding a colorant, this processcomprising the steps of: forming an external wall by curing a region ofprescribed width along the contour line of said colored region; adding acolorant to a liquid-phase region inside said external wall; and curingsaid colored region.
 5. The process for producing colored shaped articleaccording to claim 4, wherein a step of forming partition walls bycuring the partition zones of prescribed thickness inside the regionwhich is to be colored is implemented prior to the step of adding acolorant.
 6. The process for producing colored shaped article accordingto claim 4, wherein said colored region is formed by adding a prescribedamounts of the colorant at prescribed distance intervals by using anaddition mechanism displaced by feedback-corrected pulse signals.
 7. Theprocess for producing colored shaped article according to claim 4,wherein said step of adding a colorant comprises the steps of: removingthe liquid-phase, curable resin present in said region which is to becolored; and adding the colorant into said region after the removal ofsaid curable resin.
 8. The process for producing colored shaped articleaccording to claim 4, wherein the addition of colorants of a pluralityof colors into said region which is to be colored is conducted by addingthe colorants in a sequence starting from the colorant with a color ofthe highest priority based on the predetermined order of priority.
 9. Ashaping apparatus for forming a desired shaped article by lamination andshaping of a liquid-phase, curable resin, this apparatus comprising anaddition mechanism that can be displaced in at least the horizontaldirection to add a liquid-phase or powdered colorant to saidliquid-phase, curable resin.
 10. The shaping apparatus according toclaim 9, wherein said addition mechanism is a needle mechanismcomprising a first colorant supply hole extending in the axial directionthereof and a second colorant supply hole perpendicular to the axialdirection.
 11. The shaping apparatus according to claim 10, wherein saidneedle mechanism has a strength and shape that enable the needlemechanism to be inserted into said liquid-phase, curable resin and todisplaced three-dimensionally in said curable resin.